<?php
/**
 * Created by PhpStorm.
 * User: 姜伟
 * Date: 2017/10/9 0009
 * Time: 12:27
 */
namespace SyCache\Lite;

/**
 * Fast, light and safe Cache Class
 *
 * Cache_Lite is a fast, light and safe cache system. It's optimized
 * for file containers. It is fast and safe (because it uses file
 * locking and/or anti-corruption tests).
 *
 * There are some examples in the 'docs/examples' file
 * Technical choices are described in the 'docs/technical' file
 *
 * Memory Caching is from an original idea of
 * Mike BENOIT <ipso@snappymail.ca>
 *
 * Nota : A chinese documentation (thanks to RainX <china_1982@163.com>) is
 * available at :
 * http://rainx.phpmore.com/manual/cache_lite.html
 *
 * @package Cache_Lite
 * @category Caching
 * @author Fabien MARTY <fab@php.net>
 * @author Markus Tacker <tacker@php.net>
 */

define('CACHE_LITE_ERROR_RETURN', 1);
define('CACHE_LITE_ERROR_DIE', 8);

class CacheLite
{
    // --- Private properties ---

    /**
     * Directory where to put the cache files
     * (make sure to add a trailing slash)
     *
     * @var string $_cacheDir
     */
    public $_cacheDir = '/tmp/';

    /**
     * Enable / disable caching
     *
     * (can be very usefull for the debug of cached scripts)
     *
     * @var boolean $_caching
     */
    public $_caching = true;

    /**
     * Cache lifetime (in seconds)
     *
     * If null, the cache is valid forever.
     *
     * @var int $_lifeTime
     */
    public $_lifeTime = 3600;

    /**
     * Enable / disable fileLocking
     *
     * (can avoid cache corruption under bad circumstances)
     *
     * @var boolean $_fileLocking
     */
    public $_fileLocking = true;

    /**
     * Timestamp of the last valid cache
     *
     * @var int $_refreshTime
     */
    public $_refreshTime;

    /**
     * File name (with path)
     *
     * @var string $_file
     */
    public $_file;

    /**
     * File name (without path)
     *
     * @var string $_fileName
     */
    public $_fileName;

    /**
     * Enable / disable write control (the cache is read just after writing to detect corrupt entries)
     *
     * Enable write control will lightly slow the cache writing but not the cache reading
     * Write control can detect some corrupt cache files but maybe it's not a perfect control
     *
     * @var boolean $_writeControl
     */
    public $_writeControl = true;

    /**
     * Enable / disable read control
     *
     * If enabled, a control key is embeded in cache file and this key is compared with the one
     * calculated after the reading.
     *
     * @var boolean $_writeControl
     */
    public $_readControl = true;

    /**
     * Type of read control (only if read control is enabled)
     *
     * Available values are :
     * 'md5' for a md5 hash control (best but slowest)
     * 'crc32' for a crc32 hash control (lightly less safe but faster, better choice)
     * 'strlen' for a length only test (fastest)
     *
     * @var boolean $_readControlType
     */
    public $_readControlType = 'crc32';

    /**
     * Pear error mode (when raiseError is called)
     *
     * (see PEAR doc)
     *
     * @see setToDebug()
     * @var int $_pearErrorMode
     */
    public $_pearErrorMode = CACHE_LITE_ERROR_RETURN;

    /**
     * Current cache id
     *
     * @var string $_id
     */
    public $_id;

    /**
     * Current cache group
     *
     * @var string $_group
     */
    public $_group;

    /**
     * Enable / Disable "Memory Caching"
     *
     * NB : There is no lifetime for memory caching !
     *
     * @var boolean $_memoryCaching
     */
    public $_memoryCaching = false;

    /**
     * Enable / Disable "Only Memory Caching"
     * (be carefull, memory caching is "beta quality")
     *
     * @var boolean $_onlyMemoryCaching
     */
    public $_onlyMemoryCaching = false;

    /**
     * Memory caching array
     *
     * @var array $_memoryCachingArray
     */
    public $_memoryCachingArray = [];

    /**
     * Memory caching counter
     *
     * @var int $memoryCachingCounter
     */
    public $_memoryCachingCounter = 0;

    /**
     * Memory caching limit
     *
     * @var int $memoryCachingLimit
     */
    public $_memoryCachingLimit = 1000;

    /**
     * File Name protection
     *
     * if set to true, you can use any cache id or group name
     * if set to false, it can be faster but cache ids and group names
     * will be used directly in cache file names so be carefull with
     * special characters...
     *
     * @var boolean $fileNameProtection
     */
    public $_fileNameProtection = true;

    /**
     * Enable / disable automatic serialization
     *
     * it can be used to save directly datas which aren't strings
     * (but it's slower)
     *
     * @var boolean $_serialize
     */
    public $_automaticSerialization = false;

    /**
     * Disable / Tune the automatic cleaning process
     *
     * The automatic cleaning process destroy too old (for the given life time)
     * cache files when a new cache file is written.
     * 0               => no automatic cache cleaning
     * 1               => systematic cache cleaning
     * x (integer) > 1 => automatic cleaning randomly 1 times on x cache write
     *
     * @var int $_automaticCleaning
     */
    public $_automaticCleaningFactor = 0;

    /**
     * Nested directory level
     *
     * Set the hashed directory structure level. 0 means "no hashed directory
     * structure", 1 means "one level of directory", 2 means "two levels"...
     * This option can speed up Cache_Lite only when you have many thousands of
     * cache file. Only specific benchs can help you to choose the perfect value
     * for you. Maybe, 1 or 2 is a good start.
     *
     * @var int $_hashedDirectoryLevel
     */
    public $_hashedDirectoryLevel = 0;

    /**
     * Umask for hashed directory structure
     *
     * @var int $_hashedDirectoryUmask
     */
    public $_hashedDirectoryUmask = 0700;

    /**
     * API break for error handling in CACHE_LITE_ERROR_RETURN mode
     *
     * In CACHE_LITE_ERROR_RETURN mode, error handling was not good because
     * for example save() method always returned a boolean (a PEAR_Error object
     * would be better in CACHE_LITE_ERROR_RETURN mode). To correct this without
     * breaking the API, this option (false by default) can change this handling.
     *
     * @var boolean
     */
    public $_errorHandlingAPIBreak = false;

    public $_hashedDirectoryGroup = null;

    public $_cacheFileMode = null;

    public $_cacheFileGroup = null;

    // --- Public methods ---

    /**
     * Constructor
     *
     * $options is an assoc. Available options are :
     * $options = array(
     *     'cacheDir' => directory where to put the cache files (string),
     *     'caching' => enable / disable caching (boolean),
     *     'lifeTime' => cache lifetime in seconds (int),
     *     'fileLocking' => enable / disable fileLocking (boolean),
     *     'writeControl' => enable / disable write control (boolean),
     *     'readControl' => enable / disable read control (boolean),
     *     'readControlType' => type of read control 'crc32', 'md5', 'strlen' (string),
     *     'pearErrorMode' => pear error mode (when raiseError is called) (cf PEAR doc) (int),
     *     'memoryCaching' => enable / disable memory caching (boolean),
     *     'onlyMemoryCaching' => enable / disable only memory caching (boolean),
     *     'memoryCachingLimit' => max nbr of records to store into memory caching (int),
     *     'fileNameProtection' => enable / disable automatic file name protection (boolean),
     *     'automaticSerialization' => enable / disable automatic serialization (boolean),
     *     'automaticCleaningFactor' => distable / tune automatic cleaning process (int),
     *     'hashedDirectoryLevel' => level of the hashed directory system (int),
     *     'hashedDirectoryUmask' => umask for hashed directory structure (int),
     *     'errorHandlingAPIBreak' => API break for better error handling ? (boolean)
     *     'hashedDirectoryGroup' => group of hashed directory structure (int | string) (see function chgrp)
     *     'cacheFileMode' => filesystem mode of newly created cache files (int)
     *     'cacheFileGroup' => group of newly created cache files (int | string) (see function chgrp)
     * );
     *
     * If sys_get_temp_dir() is available and the
     * 'cacheDir' option is not provided in the
     * constructor options array its output is used
     * to determine the suitable temporary directory.
     *
     * @see http://de.php.net/sys_get_temp_dir
     * @see http://pear.php.net/bugs/bug.php?id=18328
     *
     * @param array $options options
     * @access public
     */
    public function __construct($options = [null])
    {
        foreach ($options as $key => $value) {
            $this->setOption($key, $value);
        }
        if (!isset($options['cacheDir']) && function_exists('sys_get_temp_dir')) {
            $this->setOption('cacheDir', sys_get_temp_dir() . DIRECTORY_SEPARATOR);
        }
    }

    /**
     * PHP4 constructor for backwards compatibility with older code
     *
     * @param array $options Options
     */
    public function Cache_Lite($options = [null])
    {
        self::__construct($options);
    }

    /**
     * Generic way to set a Cache_Lite option
     *
     * see Cache_Lite constructor for available options
     *
     * @var string $name name of the option
     * @var mixed $value value of the option
     * @access public
     * @param mixed $name
     * @param mixed $value
     */
    public function setOption($name, $value)
    {
        $availableOptions = ['errorHandlingAPIBreak', 'hashedDirectoryUmask', 'hashedDirectoryLevel', 'automaticCleaningFactor', 'automaticSerialization', 'fileNameProtection', 'memoryCaching', 'onlyMemoryCaching', 'memoryCachingLimit', 'cacheDir', 'caching', 'lifeTime', 'fileLocking', 'writeControl', 'readControl', 'readControlType', 'pearErrorMode', 'hashedDirectoryGroup', 'cacheFileMode', 'cacheFileGroup'];
        if (in_array($name, $availableOptions, true)) {
            $property = '_' . $name;
            $this->$property = $value;
        }
    }

    /**
     * Test if a cache is available and (if yes) return it
     *
     * @param string $id cache id
     * @param string $group name of the cache group
     * @param boolean $doNotTestCacheValidity if set to true, the cache validity won't be tested
     * @return string data of the cache (else : false)
     * @access public
     */
    public function get($id, $group = 'default', $doNotTestCacheValidity = false)
    {
        $this->_id = $id;
        $this->_group = $group;
        $data = false;
        if ($this->_caching) {
            $this->_setRefreshTime();
            $this->_setFileName($id, $group);
            clearstatcache();
            if ($this->_memoryCaching) {
                if (isset($this->_memoryCachingArray[$this->_file])) {
                    if ($this->_automaticSerialization) {
                        return unserialize($this->_memoryCachingArray[$this->_file]);
                    }
                    return $this->_memoryCachingArray[$this->_file];
                }
                if ($this->_onlyMemoryCaching) {
                    return false;
                }
            }
            if (($doNotTestCacheValidity) || (is_null($this->_refreshTime))) {
                if (file_exists($this->_file)) {
                    $data = $this->_read();
                }
            } else {
                if ((file_exists($this->_file)) && (@filemtime($this->_file) > $this->_refreshTime)) {
                    $data = $this->_read();
                }
            }
            if (($data) and ($this->_memoryCaching)) {
                $this->_memoryCacheAdd($data);
            }
            if (($this->_automaticSerialization) and (is_string($data))) {
                $data = unserialize($data);
            }
            return $data;
        }
        return false;
    }

    /**
     * Save some data in a cache file
     *
     * @param string $data data to put in cache (can be another type than strings if automaticSerialization is on)
     * @param string $id cache id
     * @param string $group name of the cache group
     * @return boolean true if no problem (else : false or a PEAR_Error object)
     * @access public
     */
    public function save($data, $id = null, $group = 'default')
    {
        if ($this->_caching) {
            if ($this->_automaticSerialization) {
                $data = serialize($data);
            }
            if (isset($id)) {
                $this->_setFileName($id, $group);
            }
            if ($this->_memoryCaching) {
                $this->_memoryCacheAdd($data);
                if ($this->_onlyMemoryCaching) {
                    return true;
                }
            }
            if ($this->_automaticCleaningFactor > 0 && ($this->_automaticCleaningFactor == 1 || mt_rand(1, $this->_automaticCleaningFactor) == 1)) {
                $this->clean(false, 'old');
            }
            if ($this->_writeControl) {
                $res = $this->_writeAndControl($data);
                if (is_bool($res)) {
                    if ($res) {
                        return true;
                    }
                    // if $res if false, we need to invalidate the cache
                    @touch($this->_file, time() - 2 * abs($this->_lifeTime));
                    return false;
                }
            } else {
                $res = $this->_write($data);
            }
            if (is_object($res)) {
                // $res is a PEAR_Error object
                if (!($this->_errorHandlingAPIBreak)) {
                    return false; // we return false (old API)
                }
            }
            return $res;
        }
        return false;
    }

    /**
     * Remove a cache file
     *
     * @param string $id cache id
     * @param string $group name of the cache group
     * @param boolean $checkbeforeunlink check if file exists before removing it
     * @return boolean true if no problem
     * @access public
     */
    public function remove($id, $group = 'default', $checkbeforeunlink = false)
    {
        $this->_setFileName($id, $group);
        if ($this->_memoryCaching) {
            if (isset($this->_memoryCachingArray[$this->_file])) {
                unset($this->_memoryCachingArray[$this->_file]);
                $this->_memoryCachingCounter = $this->_memoryCachingCounter - 1;
            }
            if ($this->_onlyMemoryCaching) {
                return true;
            }
        }
        if ($checkbeforeunlink) {
            if (!file_exists($this->_file)) {
                return true;
            }
        }
        return $this->_unlink($this->_file);
    }

    /**
     * Clean the cache
     *
     * if no group is specified all cache files will be destroyed
     * else only cache files of the specified group will be destroyed
     *
     * @param string $group name of the cache group
     * @param string $mode flush cache mode : 'old', 'ingroup', 'notingroup',
     *                                        'callback_myFunction'
     * @return boolean true if no problem
     * @access public
     */
    public function clean($group = false, $mode = 'ingroup')
    {
        return $this->_cleanDir($this->_cacheDir, $group, $mode);
    }

    /**
     * Set to debug mode
     *
     * When an error is found, the script will stop and the message will be displayed
     * (in debug mode only).
     *
     * @access public
     */
    public function setToDebug()
    {
        $this->setOption('pearErrorMode', CACHE_LITE_ERROR_DIE);
    }

    /**
     * Set a new life time
     *
     * @param int $newLifeTime new life time (in seconds)
     * @access public
     */
    public function setLifeTime($newLifeTime)
    {
        $this->_lifeTime = $newLifeTime;
        $this->_setRefreshTime();
    }

    /**
     * Save the state of the caching memory array into a cache file cache
     *
     * @param string $id cache id
     * @param string $group name of the cache group
     * @access public
     */
    public function saveMemoryCachingState($id, $group = 'default')
    {
        if ($this->_caching) {
            $array = [
                'counter' => $this->_memoryCachingCounter,
                'array' => $this->_memoryCachingArray
            ];
            $data = serialize($array);
            $this->save($data, $id, $group);
        }
    }

    /**
     * Load the state of the caching memory array from a given cache file cache
     *
     * @param string $id cache id
     * @param string $group name of the cache group
     * @param boolean $doNotTestCacheValidity if set to true, the cache validity won't be tested
     * @access public
     */
    public function getMemoryCachingState($id, $group = 'default', $doNotTestCacheValidity = false)
    {
        if ($this->_caching) {
            if ($data = $this->get($id, $group, $doNotTestCacheValidity)) {
                $array = unserialize($data);
                $this->_memoryCachingCounter = $array['counter'];
                $this->_memoryCachingArray = $array['array'];
            }
        }
    }

    /**
     * Return the cache last modification time
     *
     * BE CAREFUL : THIS METHOD IS FOR HACKING ONLY !
     *
     * @return int last modification time
     */
    public function lastModified()
    {
        return @filemtime($this->_file);
    }

    /**
     * Trigger a PEAR error
     *
     * To improve performances, the PEAR.php file is included dynamically.
     * The file is so included only when an error is triggered. So, in most
     * cases, the file isn't included and perfs are much better.
     *
     * @param string $msg error message
     * @param int $code error code
     * @access public
     */
    public function raiseError($msg, $code)
    {
        include_once 'PEAR.php';
        return PEAR::raiseError($msg, $code, $this->_pearErrorMode);
    }

    /**
     * Extend the life of a valid cache file
     *
     * see http://pear.php.net/bugs/bug.php?id=6681
     *
     * @access public
     */
    public function extendLife()
    {
        @touch($this->_file);
    }

    // --- Private methods ---

    /**
     * Compute & set the refresh time
     *
     * @access private
     */
    public function _setRefreshTime()
    {
        if (is_null($this->_lifeTime)) {
            $this->_refreshTime = null;
        } else {
            $this->_refreshTime = time() - $this->_lifeTime;
        }
    }

    /**
     * Remove a file
     *
     * @param string $file complete file path and name
     * @return boolean true if no problem
     * @access private
     */
    public function _unlink($file)
    {
        if (!@unlink($file)) {
            return $this->raiseError('Cache_Lite : Unable to remove cache !', -3);
        }
        return true;
    }

    /**
     * Recursive function for cleaning cache file in the given directory
     *
     * @param string $dir directory complete path (with a trailing slash)
     * @param string $group name of the cache group
     * @param string $mode flush cache mode : 'old', 'ingroup', 'notingroup',
    'callback_myFunction'
     * @return boolean true if no problem
     * @access private
     */
    public function _cleanDir($dir, $group = false, $mode = 'ingroup')
    {
        if ($this->_fileNameProtection) {
            $motif = ($group) ? 'cache_' . md5($group) . '_' : 'cache_';
        } else {
            $motif = ($group) ? 'cache_' . $group . '_' : 'cache_';
        }
        if ($this->_memoryCaching) {
            foreach ($this->_memoryCachingArray as $key => $v) {
                if (strpos($key, $motif) !== false) {
                    unset($this->_memoryCachingArray[$key]);
                    $this->_memoryCachingCounter = $this->_memoryCachingCounter - 1;
                }
            }
            if ($this->_onlyMemoryCaching) {
                return true;
            }
        }
        if (!($dh = opendir($dir))) {
            return $this->raiseError('Cache_Lite : Unable to open cache directory !', -4);
        }
        $result = true;
        while (($file = readdir($dh)) !== false) {
            if (($file != '.') && ($file != '..')) {
                if (substr($file, 0, 6) == 'cache_') {
                    $file2 = $dir . $file;
                    if (is_file($file2)) {
                        switch (substr($mode, 0, 9)) {
                            case 'old':
                                // files older than lifeTime get deleted from cache
                                if (!is_null($this->_lifeTime)) {
                                    if ((time() - @filemtime($file2)) > $this->_lifeTime) {
                                        $result = ($result and ($this->_unlink($file2)));
                                    }
                                }
                                break;
                            case 'notingrou':
                                if (strpos($file2, $motif) === false) {
                                    $result = ($result and ($this->_unlink($file2)));
                                }
                                break;
                            case 'callback_':
                                $func = substr($mode, 9, strlen($mode) - 9);
                                if ($func($file2, $group)) {
                                    $result = ($result and ($this->_unlink($file2)));
                                }
                                break;
                            case 'ingroup':
                            default:
                                if (strpos($file2, $motif) !== false) {
                                    $result = ($result and ($this->_unlink($file2)));
                                }
                                break;
                        }
                    }
                    if ((is_dir($file2)) and ($this->_hashedDirectoryLevel > 0)) {
                        $result = ($result and ($this->_cleanDir($file2 . '/', $group, $mode)));
                    }
                }
            }
        }
        return $result;
    }

    /**
     * Touch the cache file while are recreating it to avoid
     * launch this task more then once when necessary
     * When the cache recreated and Added in Cache Memory
     * @return void
     * @access private
     */
    public function _touchCacheFile()
    {
        if (file_exists($this->_file)) {
            @touch($this->_file);
        }
    }
    /**
     * Add some date in the memory caching array
     *
     * @param string $data data to cache
     * @access private
     */
    public function _memoryCacheAdd($data)
    {
        $this->_touchCacheFile();
        $this->_memoryCachingArray[$this->_file] = $data;
        if ($this->_memoryCachingCounter >= $this->_memoryCachingLimit) {
            list($key) = each($this->_memoryCachingArray);
            unset($this->_memoryCachingArray[$key]);
        } else {
            $this->_memoryCachingCounter = $this->_memoryCachingCounter + 1;
        }
    }

    /**
     * Make a file name (with path)
     *
     * @param string $id cache id
     * @param string $group name of the group
     * @access private
     */
    public function _setFileName($id, $group)
    {
        if ($this->_fileNameProtection) {
            $suffix = 'cache_' . md5($group) . '_' . md5($id);
        } else {
            $suffix = 'cache_' . $group . '_' . $id;
        }
        $root = $this->_cacheDir;
        if ($this->_hashedDirectoryLevel > 0) {
            $hash = md5($suffix);
            for ($i = 0; $i < $this->_hashedDirectoryLevel; $i++) {
                $root = $root . 'cache_' . substr($hash, 0, $i + 1) . '/';
            }
        }
        $this->_fileName = $suffix;
        $this->_file = $root . $suffix;
    }

    /**
     * Read the cache file and return the content
     *
     * @return string content of the cache file (else : false or a PEAR_Error object)
     * @access private
     */
    public function _read()
    {
        $fp = @fopen($this->_file, 'rb');
        if ($fp) {
            if ($this->_fileLocking) {
                @flock($fp, LOCK_SH);
            }
            clearstatcache();
            $length = @filesize($this->_file);
            $mqr = get_magic_quotes_runtime();
            if ($mqr) {
                set_magic_quotes_runtime(0);
            }
            if ($this->_readControl) {
                $hashControl = @fread($fp, 32);
                $length = $length - 32;
            }

            if ($length) {
                $data = '';
                // See https://bugs.php.net/bug.php?id=30936
                // The 8192 magic number is the chunk size used internally by PHP.
                while (!feof($fp)) {
                    $data .= fread($fp, 8192);
                }
            } else {
                $data = '';
            }
            if ($mqr) {
                set_magic_quotes_runtime($mqr);
            }
            if ($this->_fileLocking) {
                @flock($fp, LOCK_UN);
            }
            @fclose($fp);
            if ($this->_readControl) {
                $hashData = $this->_hash($data, $this->_readControlType);
                if ($hashData != $hashControl) {
                    if (!(is_null($this->_lifeTime))) {
                        @touch($this->_file, time() - 2 * abs($this->_lifeTime));
                    } else {
                        @unlink($this->_file);
                    }
                    return false;
                }
            }
            return $data;
        }
        return $this->raiseError('Cache_Lite : Unable to read cache !', -2);
    }

    /**
     * Write the given data in the cache file
     *
     * @param string $data data to put in cache
     * @return boolean true if ok (a PEAR_Error object else)
     * @access private
     */
    public function _write($data)
    {
        if ($this->_hashedDirectoryLevel > 0) {
            $hash = md5($this->_fileName);
            $root = $this->_cacheDir;
            for ($i = 0; $i < $this->_hashedDirectoryLevel; $i++) {
                $root = $root . 'cache_' . substr($hash, 0, $i + 1) . '/';
                if (!(@is_dir($root))) {
                    if (@mkdir($root)) {
                        @chmod($root, $this->_hashedDirectoryUmask);
                        if (! is_null($this->_hashedDirectoryGroup)) {
                            @chgrp($root, $this->_hashedDirectoryGroup);
                        }
                    }
                }
            }
        }
        // if both _cacheFileMode and _cacheFileGroup is null, then we don't need to call
        // file_exists (see below: if ($is_newfile) ...)
        $is_newfile = (! is_null($this->_cacheFileMode) || !is_null($this->_cacheFileGroup))
                      && ! @file_exists($this->_file);
        $fp = @fopen($this->_file, 'wb');
        if ($fp) {
            if ($this->_fileLocking) {
                @flock($fp, LOCK_EX);
            }
            if ($is_newfile) {
                if (! is_null($this->_cacheFileMode)) {
                    @chmod($this->_file, $this->_cacheFileMode);
                }
                if (! is_null($this->_cacheFileGroup)) {
                    @chgrp($this->_file, $this->_cacheFileGroup);
                }
            }
            if ($this->_readControl) {
                @fwrite($fp, $this->_hash($data, $this->_readControlType), 32);
            }
            $mqr = get_magic_quotes_runtime();
            if ($mqr) {
                set_magic_quotes_runtime(0);
            }
            @fwrite($fp, $data);
            if ($mqr) {
                set_magic_quotes_runtime($mqr);
            }
            if ($this->_fileLocking) {
                @flock($fp, LOCK_UN);
            }
            @fclose($fp);
            return true;
        }
        return $this->raiseError('Cache_Lite : Unable to write cache file : ' . $this->_file, -1);
    }

    /**
     * Write the given data in the cache file and control it just after to avoir corrupted cache entries
     *
     * @param string $data data to put in cache
     * @return boolean true if the test is ok (else : false or a PEAR_Error object)
     * @access private
     */
    public function _writeAndControl($data)
    {
        $result = $this->_write($data);
        if (is_object($result)) {
            return $result; # We return the PEAR_Error object
        }
        $dataRead = $this->_read();
        if (is_object($dataRead)) {
            return $dataRead; # We return the PEAR_Error object
        }
        if ((is_bool($dataRead)) && (!$dataRead)) {
            return false;
        }
        return ($dataRead == $data);
    }

    /**
     * Make a control key with the string containing datas
     *
     * @param string $data data
     * @param string $controlType type of control 'md5', 'crc32' or 'strlen'
     * @return string control key
     * @access private
     */
    public function _hash($data, $controlType)
    {
        switch ($controlType) {
            case 'md5':
                return md5($data);
            case 'crc32':
                return sprintf('% 32d', crc32($data));
            case 'strlen':
                return sprintf('% 32d', strlen($data));
            default:
                return $this->raiseError('Unknown controlType ! (available values are only \'md5\', \'crc32\', \'strlen\')', -5);
        }
    }
}
